The Italian has lauded the return of the Rossoneri favourite after four years away and revealed he could tinker with his formation to accommodate his new signing Massimiliano Allegri believes Kaka has already improved AC Milan by raising the level of self-confidence throughout the squad. The Brazil midfielder - who played for the Rossoneri between 2003 to 2009 - returned to San Siro on a free transfer last week after four years with Real Madrid. He played 45 minutes in a 4-0 friendly win against Chiasso of Switzerland on Saturday wearing the captain's armband and showed enough to suggest he could be a key player for Allegri this season. "Kaka has great quality is a champion and his presence raises the level of self-confidence throughout the squad" Allegri told Milan Channel.